Method of purifying burner-gas.



C. L. REESE.

METHOD OF PURIFYING BURNER GAS.

APPLICATION FILED MAY 9, 1910i INVENTOH WITNESSES: M (I 82 10 ing is a full, clear, and eXact 20 S0, to S 35 bonate, or hydrate,

' UNITED STATES NEMOURS POWDER COMPANY, OF NEW JERSEY.

CHARLES L. E'EEsE, WILMINGTON, DELAWARE, ASSIGNOR To E. r. DUPONT'DE WILMINGTON, DELAWARE, A CORPORATION OF METHOD OF PURIFYING BURNER-GAS.

Specification of Letters Patent. Patented Apr. 18, 1911.

Application filed May 9, 1910. Serial No. 560,158.

of Delaware, have invented a new and useful improvement in methods of purifying burner-gas produced in the manufacture of sulfuric acid from sulfur or' sulfur substances or sulfid ores, of which the followdescription. The object ofmiy invention is to remove chlorin, fluorin, arsenic, lead and other im-' purities carried by sulfuric acid mist present in burner gas produced in the manufacture of sulfuric acid. The minute particles of these impurities form a nucleus for minute globules of sulfuric acid. These impurities lower the yield of sulfuric acid by deteriorating the catalytic used to convert the Efiorts have been made to remove these impurities by scrubbing the gas with sulfuric acid and subsequently filtering the gas through fibrous materials like asbestos. It is diflicult with this method to maintain the filters in proper condition for any substantial period of time and, further, the method is very expensive. Mineral wool used as a substitute in part for the asbestos lowers the cost but the life of the filter is lessened. The use of alkaline liquids has the objection that the gas becomes saturated with moisture and thus the average strength of the total product of the plant is reduced. I have discovered that if dry lime, oxid, carbe used as the filtering material the removal of these impurities is obtained without any'of the disadvantages hereinbefore pointed out.

By tests with my improved filter I have 40 found that the gas ,com ng therefrom is optically ure at all times, a. 6., when a beam of sun i ht is passed through the gas, by means 0 a lens, no mist could be seen. When the gas passed through a depth of six feet of lime, samples taken from the top showed that arsenic and chlorin and H SO had been absorbed, whereas samples taken from fifteen inches below the top where the gas entered, showed that practically none of the impurities or sulfuric acid had penetrated.

With myimproved method any chlorin, fluorin, arsenic, lead or other solid impurities carried over by the sulfuric acid mist is removed, not only increasing the conversion, but also protecting the pumps or blowers and prolonging the life of the contact mass, and for which latter, with the use of these filters, should be a permanent protection.

Of course, compounds containing lime such, for instance, as dolomite, which con tains both @210 and MgO, can be used with the same efiect as lime alone.

My invention can be carried out in the apparatus shown in the accompanying drawings in whichv Figure 1 is a general arrangement of the apparatus, tially broken away, of a portion of the apparatus.

Pyrites is burned in burner A. The burner gases are passed first through a dust chamber B, where the heavier dust is deposited, next through cooling flue L, where the excess heat is removed, thence through scrubbers 6 in which the gas is scrubbed and dried with sulfuric acid of about 60 B. Thence, through separator D, in which the spray formed in scrubbers is removed. Thence, through a set of filters containing inert material, such as quartz, coke, sand,

-etc., in which the greater portion of the sulfuric acid mist is removed. Finally, the gas is passed through series of lime filters F, preferably from top to bottom, where the last traces of impurity are removed, due to the combination of the stronger acids with lime and the mechanical retention of impurities carried by the sulfuric acid mist after the latter has been broken up by combination with lime.

The previously described apparatus is maintained under diminished pressure by blower G, from which the gas passes under pressure through preheater I H, into converter I, where the S0 is converted inthe presence of contact material to sulfuric anhydrid, which is absorbed by means of sul-.

furic acid in passing through absorbers J and K. The blower is located preferably after the liniefilter, as shown in the draw ing, but may be placed at other polnts 1n the system as desired.

The gases pass through the filter at a temperature lower than that of 130 Fahrenheit. As may be seen, the burner gases are first cooled, then dried by sulfuric acid and finally passed through a filter containmg Fig. 2 is an enlarged view,par-

dry lime, which may be in the form of oxid, carbonate or hydrate. The removal of the impurities is obtained without any of the disadvantages hereinbefore pointed out. The lime combines with any sulfuric acid, which maybe present in the gas in the form of mist, and impurities carried by the sulfuric acid. The lime also combines with any hydrochloric acid and hydrofluoric acidpresent, but does not combine with the S0 Neither sulfite nor bisulfite is formed and the lime does not slake, except in quantities equivalent to the sulfuric acid, hydrochloric acid and hydrofluoric acid present in the gas. 4

Having now fully described myinvention, what I claim and desire to protect by Letters Patent is 1. The method of removing impurities from burner gases, produced in the manufacture of sulfuric acid, which consists in coolat the same time retains the gases with ing and drying said gases, and passing the.

same through a dry lime filter.

2. The method of removing impurities from burner gases, produced in the manufacture of sulfuric acid, which consists in first cooling the burner gases, then drying said gases and then passing said gases through a'dry lime filter.

3. The method of removing impurities from burner gases produced in the manufacture of sulfuric acid, which consists in first cooling said gases, then scrubbing said sulfuric acid, and then passing said gases through a dry lime filter.

- In testimony-of which invention, I have hereunto set my hand, at Wilmington, Delaware, on this 5th day of May, 1910.

CHARLES L. REESE:

Witnesses: v

LEON O. BRYAN,

WM. M. VVHITTEN, J r, 

